1. Field of the Disclosure
The present application relates to a flexible display device and a manufacturing method thereof. More particularly, the present application relates to a flexible display device which allows elements to be stably formed on a flexible substrate and enhances flexibility of the flexible substrate and reliability, and to a method of manufacturing the same.
2. Description of the Related Art
Nowadays, the world has seen rapid advances in the electronic display field for visually representing an information. As a result, a variety of flat panel display devices that are slim, light weight, and with low power consumption have been developed. Also, the flat panel display devices have been rapidly replacing the existing cathode ray tubes (CRTs).
As examples of the flat panel display devices, liquid crystal display (LCD) devices, organic light emitting display (OLED) devices, electrophoretic display (electric paper display (EPD)) devices, plasma display panel device (PDPs), field emission display(FED) devices, electroluminescence display devices (ELDs), elector-wetting display (EWD) devices, and so on have been introduced. Such flat panel display devices commonly include a flat display panel, as a necessary component, to display images. The flat display panel is configured with a pair of combined substrates which face each other with having an inherent light emitting or polarizing material layer therebetween.
Also, as the display devices are actively developed, may have enhanced esthetics and provide useful multi-functions to distinguish the products. In general, a related art display device includes a flat panel which uses a glass substrate. Due to this, it is difficult to diversify the design. Moreover, because of large flat areas, the related flat panel devices have a different distance between a main viewing area and its central portion and the main viewing area and its side portion. In other words, the flat panel designs have a different distance between its central portion and its side portion with respect to the main viewing area.
To address this matter, a flexible display device using a flexible material such as a plastic material and so on is developed. The flexible display device can be curved and designed in a variety of shapes, unlike the flat panel display devices of the related art. Such a flexible display device can be more attractive as a next generation display device to replace a monitor of a portable computer, an electronic newspaper, a smart card, and printed media such as books, newspapers, magazines and so on.
To be attractive, the flexible display device must maintain display performance when it is bent. However, the flexible display device can cause display defects when bent or curved. This results from the fact that the flexible display device includes multiple thin film layers and electronic elements which are formed on a flexible substrate. In other words, the thin film layers and the electronic elements can be formed by stacking inorganic materials.
When the flexible display device is severely bent or curved, a bending stress is transferred to the thin film layers and the electronic elements. The bending stress forces the thin film layers to be cracked or deteriorated. Due to this, physical and electrical properties of the electronic elements can deteriorate.